Although numerous industrial processes have been used to manufacture acetone, conventionally acetone is obtained as a co-product of phenol production by the Hock Process. In this process, benzene is alkylated in the presence of a Friedel-Crafts catalyst with propylene to produce cumene, which in turn is oxidized to cumene hydroperoxide (CHP). CHP is then hydrolyzed in an acidic medium to yield phenol and acetone. There are several variations of the Hock Process. For example, U.S. Pat. No. 5,015,786 describes the preparation of cumene by alkylating an aromatic compound, the preparation of phenol via cumene, and the alkylation of an aromatic compound using an alcohol as the alkylating agent. U.S. Pat. No. 4,310,712 describes a process where CHP is decomposed to phenol and acetone by mixing it with acetone and a catalyst. U.S. Pat. No. 7,109,385 describes a process for producing a phenol product generally comprising the first step of reacting CHP and water with an acid catalyst to produce the phenol product, and the second step of passing the phenol product through a second reactor to decompose the residual CHP.
When there is a demand imbalance between phenol and acetone, however, the co-production using the Hock Process is not efficient or economic.
Other industrial process for producing acetone include dehydrogenation of 2-propanol, as described in GB823514. Propylene is absorbed in concentrated sulfuric acid to produce isopropyl sulfate, which is then hydrolyzed to 2-propanol. The 2-propanol is then oxidized to produce acetone. U.S. Pat. No. 3,981,923 describes alumina-supported platinum or rhodium catalysts used for dehydrogenating lower secondary alcohols to ketones. U.S. Pat. No. 5,103,066 describes the catalytic dehydrogenation of alcohols to produce ketones and/or aldehydes using catalyst that comprises a platinum group metal and a non-acidic microporous crystalline support.
Each of these industrial processes are dependent on propylene. Since propylene is produced from natural gas liquids or refinery streams, its price has shown considerable volatility. This instability has impacted the economics of acetone manufacture. In addition, impurities in propylene often form unwanted by-products. Propylene is manufactured generally using crude oil as the starting material. Crude oil, however, contains sulfur compounds and various heavy metals, and these impurities are sometimes carried in propylene as trace contaminants during its manufacturing process. For example, carbonyl sulfide (COS) as a sulfur compound or arsenic as a heavy metal contaminant in propylene act as a catalyst poison in cumene preparation, thus disturbing normal progress of the cumene synthesis. Therefore, a strict purification process is needed to avoid contamination. Types and quantity of these contaminants, however, vary depending on not only the crude oil source but also the difference in the process conditions for the preparation of propylene from crude oil. Such irregularity burdens the propylene purification process with exceptionally complex and severe steps. Furthermore, conventional processes employ hazardous compounds such as concentrated sulfuric acid and benzene, a volatile carcinogen.
Alternatively, acetone may be produced by reacting formaldehyde with methyl chloride to produce acetone and hydrogen chloride. Methyl chloride is a toxic gas however, and formaldehyde is a known carcinogen. U.S. Pat. No. 6,933,414 describes a method for producing acetone via the reaction of formaldehyde with methyl chloride.
Various catalysts for converting acetic acid to acetone have been proposed. U.S. Pat. No. 1,892,742 describes a ketonization catalyst for converting acetic acid, acetylene, acetaldehyde, and ethyl acetate to acetone. The catalyst is porous charcoal containing oxides of iron, calcium, zinc, cerium, and thorium. U.S. Pat. No. 1,315,544 describes converting acetic acid to acetone using a catalyst comprising metallic iron in fine shavings. U.S. Pat. No. 2,697,729 describes a liquid phase pyrolysis of carboxylic acid and esters thereof to acetone using an activated alumina catalyst. U.S. Pat. No. 3,446,334 describes a process of converting aldehyde and acid to ketone using a catalyst containing lithium oxide on activated alumina. U.S. Pat. No. 4,754,074 describes converting carboxylic acids to aliphatic dialkyl ketone using a manganese dioxide on alumina catalyst. U.S. Pat. No. 6,265,618 discloses a process for the preparation of ketones, in particular cyclopropyl ketones, by contacting one or more carboxylic acids with a niobium catalyst at elevated temperatures. US Pub. No. 2011/0185628 described a ketonization reaction using a thorium oxide that converts acetic acid to acetone.
Therefore, it is an object of the present invention is to minimize the disadvantages of existing commercial processes for the production of acetone. One object of the present invention is to free producers from their dependence on propylene. Another object of the present invention is to provide a process in which acetone is the primary product. These and other objects, features, and advantages will be apparent from the following description.